Thermosetting foam products prepared by the use of phenol-formaldehyde, blowing agents and an acidic catalyst typically are characterized by having a fairly brittle foam structure with low compression strength and exhibiting high friability properties.
Furfural is an aldehyde which has been employed in various condensation reactions with many types of compounds, such as, for example, phenol, to produce condensation products. Phenol furfural resin compositions have been prepared, for example, by employing a polyalkylene polyphenol and furfural, which provides for a flexible, thermosetting resin product suitable for use in coatings and as molding compounds. Such phenol furfural resin compositions and others are described, for example, in U.S. Pat. Nos. 3,471,443 and 3,244,648.
In the parent application, it has been disclosed that thermosetting foam products of low friability and good flame resistance can be prepared by reacting a resole resin of phenol and formaldehyde with a furfuryl-alcohol polymer, particularly a substantially head-to-tail, polymerized furfurly alcohol. The thermosetting foams produced have a substantially closed-cell structure and a foam density of about 1.5 or more pounds per cubic foot. Further in the parent application, it was disclosed that, with a phenol-formaldehyde resole resin, a furfuryl-alcohol polymer must be used, and that the use of furfuryl alcohol failed to produce an acceptable foam product, in that the reactivity with the resole was so great that the resulting foamed mass overexpanded and collapsed.